Lubricant composition



Patented July 30, l 4.

LUBRICANT COMPOSITION Elmer Wade Adams and George Mervin McNulty,

Hammond, Ind., Company, Chicago, Indiana.

assignors to Standard Oil 111., a corporation of No Drawing. ApplicationJune 10, 1936, .Serial No. 84,524

17 Claims.

' trend toward increasing loads on gear teeth in other fields hasdeveloped an urgent need for special lubricants. When hypoid gears, wormgears, heavy duty bearings, alloy crank-case bearings, planetaryautomatic shifts, and the like are used under conditions of highpressure and high rubbing velocities, special types of lubricants suchas those having extreme-pressure properties and/or non-corrosiveproperties must be provided in order to reduce the wear upon such movingparts. Extreme-pressure lubricants are likewise important in cutting anddrawing operations where the oil must withstand high pressuresencountered under those condi- .tions of use.

The object of our inventionis to provide a lubricant which will givesatisfactory lubrication to bearing surfaces which are subjected to highpressures and/or high rubbing velocities as well as alloy bearings whichtend to corrode on. account of the action of the oil upon the bearing. Afurther object is to provide a lubricant which will maintain a lubricantfilm on bearing surfaces at all times. We have found that if smallamounts of certain types of organic sulfur compounds are added to thelubricating oils and soft greases, the lubricant will enable the bearingsurfaces to withstand the high pressures and high rubbing velocitieswithout noticeable wear or corrosion. Similarly, these sulfur compoundsmay be incorporated into drawing lubricants and cutting oils.

We have found that the improved lubricants can be prepared by adding asmall quantity of an alkyl disulfide, high molecular weight alkylsulfides, aryl thiocyanates and aryl isothiocyanates, xanthlcdisulfides, or xanthates to mineral lubricating oils, preferably, thoselubricating oils having a viscosity from about to 200 seconds Saybolt at210 F. These compounds may be used in oils designated as S. A. E. 20,30, 40, 50, and 60 oils. The oils designated by S. A. E. viscositynumber have Saybolt viscosities ranging from 90 to 300 seconds at F.These sulfur compounds are added in very small quantities. Amountsranging from 0.1-1.0% to 54% may be used but generally amounts rangingfrom k to 5% are satisfactory. The organic sulfur compounds may bedissolved in the oil by any conventional mixing means. If desired,calcium and aluminum soaps or other-soaps of high molecular weight fattyacids may be added to the composition to increase the viscosity orconsistency of the lubricant. These lubricants have substantially nocorrosive action upon metal surfaces.

'The sulfur-bearing compounds which may be added to mineral lubricatingoils or greases to impart improved lubricating properties thereto are asfollows:

wherein R and R1 represent alkyl groups containing at least 5 carbonatoms each or aromatic groups such as phenyl radicals and tolylradicals, however, when R represents a phenyl group, R1 may representany alkyl group; and R2 and Rs represent alkyl groups' or phenyl groups.The term alkyl is intended to include the saturated cyclic radicalsalso, such as the cyclohexyl group.

Examples of the sulfides are amyl sulfide, hexyl sulfide, cyclohexylsulfide, phenyl sulfide, ethyl phenyl sulfide, methyl phenyl sulfide,tolyl sulfide, and butyl phenyl sulfide. Examples of the disulfides areethyl disulfide, n-propyl disulfide, n-butyl disulfide, secondary butyldisulfide, tertiary butyl disulfide, cyclohexyl disulfide, ethyl propyldisulfide, amyl disulfide, heptyl disulfide, tolyl disulfide, and phenyldisulfide.

Aryl thiocyanic esters Aryl lsothiocyanic esters wherein R4 representsaryl groups such as phenyl, tolyl and naphthyl groups. Examples of thehydrocarbon thlocyanic esters are phenyl thiocyanic ester, tolylthiocyanic ester, and naphthyl thiocyanic ester. Examples of the arylisothiocyanic esters or aryl isosulphocyanic esters are phenylisosulphocyanic ester, tolyl isosulphocyanic esters, and naphthylisosulphocyanic ester. Other hydrocarbon thiocyanic esters andisothiocyanic esters may be used, particularly those bydrocarbonderivatives containing six or more carbon atoms in the hydrocarbonradical. The hydrocarbon radical may be of the straight chain type andmay contain from six, ten, twelve or more carbon atoms. The hydrocarbonesters of isothiocyanic acid impart excellent extreme-pressurelubricating properties to mineral oils.

Wherein R5, R6, and R7 represent alkyl groups. Examples of the xanthicesters are ethyl xanthate ethyl ester, methyl xanthate ethyl ester,ethyl xanthate methyl ester, ethyl xanthate butyl ester and ethylxanthate propyl ester. Examples of the xanthic disulfides are methylxanthic disulflde and ethyl xa ithic disulflde.

The load-carrying capacity of these improved lubricants when used asextreme-pressure lubricants may be determined by the extreme-pressuretesting machines such as the Almen Extreme- Pressure Lubricant TestingMachine described by Wolf and Mougey in their paper on extremepressurelubricants given at the 13th annual meeting of the A. P. I. at Houston,Texas, November 1'7, 1932.

The following table illustrates the load-carrying capacity of thecompositions when used as extreme-pressure lubricants as determined byan extreme-pressure lubricant testing machine designed and operated onthe same principle as the Almen extreme-pressure lubricant testingmachine. These lubricants may also be used to lubricate alloy bearingswhich are corroded by used mineral lubricating oils.

TABLE I Sample.-% of the following compounds dissolved in zero brightstock -(mincral oil having a viscosity of 150 Saybolt at 210 F.).

Speed of pin.-150 R. P. M.

As stated hereinbefore, the sulfur compounds may be added to the viscousmineral oil by any suitable means. Generally the sulfur compounds areadded to the mineral oil and stirred until a homogeneous mixture isobtained. Coastal oils, Mid-Continent oils and paraflin mineral oils maybe used in the preparation of our improved lubricants.

Example I Our improved lubricants may be prepared by mixing a smallamount of one of the organic sulphur compounds with a mineral oil havinga viscosity suited for the particular use of the lubricant. Aconcentrated mineral oil solution of the particular sulphur compound maybe added to a large portion of mineral oil or the desired amount of theorganic sulphur compound may be mixed with the body of mineral oil to betreated.

The hydrocarbon derivatives of the compounds herein disclosed may beprepared by any of the :onventional means. The disulfldes, for example,nay be prepared from the mercaptans occurring .n petroleum distillatesboiling within the gaso- .ine or kerosene range. A petroleum distillate,

preferably one containing a high percent of mercaptans, is agitated withcaustic. The caustic solution is separated from the hydrocarbon materialby decantation and then oxidized with any suitable chemical reagent, forexample air, or oxygen. The alkyl disulfides are then removed from theoxidized caustic solution by boiling and are collected by absorption ina mineral oil solution; if desired, they may be absorbed in the mineraloil used in the preparation of the extreme-pressure lubricant. Theoxidation with air or oxygen is preferably performed under pressure andat a temperature below the boiling point of the mercaptans in thepetroleum distillate. Generally this temperature is below 80 to 100 C.Other oxidizing agents such as hydrogen peroxide or potassiumpermanganate may be used instead of the oxygen, Also the high molecularweight alkyl disulfides may be prepared by treating hydrocarbondistillates with sodium plumbite solution and sulfur, separating theplumbite solution from the oil containing the dissolved disulfide andrecovering the alkyl disulfides by distilling the hydrocarbon oil fromthe dissolved disulfides.

The present application is a continuation-inpart of our copendingapplication Serial 718,438, filed March 31, 1934, now Patent No.2,110,281 issued March 8, 1938. While we have described our inventionwith reference to particular examples, it should be understood that ourinvention is not limited thereby, except as set forth by the claims.

We claim: I

1. An improved lubricant composition comprising a mineral lubricatingoil and a small amount of an organic sulfur compound selected from thegroup consisting of hydrocarbon thiocyanic esters having the formulaRS-CEN, wherein R represents a hydrocarbon radical containing at least 6carbon atoms; and hydrocarbon isothiocyanic esters having the generalformula R-N=C=S, wherein R represents a hydrocarbon radical containingat least 6 carbon atoms.

wherein R represents a hydrocarbon radical; and hydrocarbonisothiocyanic esters having the general formula R-N=C=S, wherein Rrepresents a hydrocarbon radical.

3. An improved lubricant composition prising a mineral lubricating oiland a amount of an aryl thiocyanic ester.

4. An improved lubricant composition prising a mineral lubricating oiland .a amount of an aryl isothiocyanic ester.

5. An improved lubricant composition comprising a mineral lubricatingoil and a small amount of an organic'compound having the formula RSCEN,wherein R represents an arcmatic hydrocarbon radical.

6. An improved lubricant composition comprising a mineral lubricatingoil and a small comsmall comsmall amount of an organic compound havingthe formula R--N=C=S, wherein R represents an arcmatic hydrocarbonradical.

7. An improved lubricant composition comprising a mineral lubricatingoil and a small esters having the general formula R--S-CEN;

wherein R represents a hydrocarbon radical containing at least 6 carbonatoms; and hydrocarbon isothiocyanic esters having the general formulaR-N=C=S, wherein R represents a hydrocarbon radical containing at least6 carbon atoms.

10. An extreme-pressure lubricant comprising a mineral lubricating oiland a small amount of a sulfur-containing organic compound selected'from the group consisting of hydrocarbon thiocyanic esters andhydrocarbon isothiocyanic esters.

11. An extreme-pressure lubricant comprising a mineral lubricating oiland a small amount of a sulfur-containing organic compound selected fromthe group consisting of aryl thiocyanic esters and aryl isothiocyanicesters.

12. An extreme-pressure lubricant comprising a mineral lubricating oiland a small amount of an organic compound having the formula wherein Rrepresents a hydrocarbon radical containing from 6 to 12 carbon atoms.

13. An improved lubricant composition prising a mineral lubricating oiland from 7% of phenyl isothiocyanate.

14. An improved lubricant composition prising a mineral lubricating oiland from 7% of a hydrocarbonphenyl isothiocyanate.

15. A composition of matter as defined in claim 1 wherein the saidorganic sulfur compound is present in amounts ranging from to 7%.

16. An improved lubricant composition comprising a mineral lubricatingoil and from to 7% of an organic compound having the formula R-SC- -N,wherein R, represents a hydrocarbon radical containing from 6 to 12carbon atoms.

17. Composition of matter comprising a viscous mineral lubricating oiland a small amount of an ester selected from the class of alkyl and arylesters of isothiocyanic acid.

ELMER WADE ADAMS. GEORGE MERVIN MCNULTY.

comto com-

